责任分散（Diffusion of responsibility）是一种社会现象，指发生在超过某一临界规模的人群中，没有明确的责任分配的趋向。这种心态可见于短语“没有一个雨滴认为是自己造成的水灾。”

责任分散可以体现为：

Diffusion of responsibility is a sociopsychological phenomenon whereby a person is less likely to take responsibility for action or inaction when others are present. Considered a form of attribution, the individual assumes that others either are responsible for taking action or have already done so. The phenomenon tends to occur in groups of people above a certain critical size and when responsibility is not explicitly assigned. Diffusion of Responsibility rarely occurs when a person is alone. But, it is thought to occur within groups of more than two people.